Alpine subduction revisited - new structural and elastic wave velocity models for improved geophysical imaging towards greater depths

重新审视高山俯冲——新的结构和弹性波速模型，用于改进更深深度的地球物理成像

• 批准号: 362665280
• 负责人: Professor Dr. Nikolaus Froitzheim
• 金额: --
• 依托单位: Institut für Geowissenschaften und Geographie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/362665280?language=en
• 关键词: Alpine; subduction; revisited; new; structural

During the Alpine orogeny, both oceanic and continental lithosphere was subducted in a complicated spatial and temporal pattern involving branching ocean basins, microcontinents, and subduction polarity reversal. This resulted in a complex structure of both crust and mantle at depth. Seismic imaging revealed high-velocity anomalies in the upper mantle, apparently dipping SE in the western and central Alps and NE in the eastern Alps. These structures have been interpreted as subducted slabs. Despite elaborate field work throughout the entire Alps and an extensive discussion of several existing seismic transects, many of the structures are still not well understood. Especially the deep structures remain enigmatic in seismic imaging, yet a better understanding is vital to constrain any tectonic model of the Alps. In this project we will study a suite of oceanic and continental rocks from the Western and Central Alps that were deformed under high and ultrahigh pressure conditions during subduction. We will determine their elastic anisotropies on the base of microstructural and textural analysis as well as by laboratory velocity measurements. This data is valuable for the interpretation of seismic imaging and for seismic modelling using the data as input parameters. With such a unique structural and petrophysical database (1) formerly subducted and exhumed oceanic and continental units of the Western and Central Alps can be characterized with respect to their position in paleo-subduction and (2) current seismic velocity anomalies under the Alps may be re-interpreted. Our data can also be instrumental and essential for a large number of projects proposed in the SPP 4D-MB, especially the seismological, the modeling and the tectonometamorphic studies. It fits in the frame of RT1 (Reorg. of Lithosphere), RT3 (Deform. of crust + mantle) and AF-E (GEOLOG. Act.).

在阿尔卑斯造山运动期间，海洋和大陆岩石圈以复杂的时空模式俯冲，涉及分支洋盆、微大陆和俯冲极性反转。这导致了深部地壳和地幔的复杂结构。地震成像显示上地幔存在高速异常，阿尔卑斯山西部和中部明显向东南倾斜，而东部阿尔卑斯山则明显向东北倾斜。这些结构被解释为俯冲板片。尽管在整个阿尔卑斯山进行了精心的现场工作，并对几个现有的地震横断面进行了广泛的讨论，但许多结构仍然没有得到很好的了解。尤其是深层结构在地震成像中仍然是个谜，但更好的理解对于约束阿尔卑斯山的任何构造模型至关重要。在这个项目中，我们将研究来自阿尔卑斯山西部和中部的一套海洋和大陆岩石，这些岩石在俯冲过程中在高压和超高压条件下变形。我们将根据微观结构和纹理分析以及实验室速度测量来确定它们的弹性各向异性。该数据对于地震成像的解释以及使用该数据作为输入参数的地震建模非常有价值。有了这样一个独特的结构和岩石物理数据库，（1）可以描述阿尔卑斯山西部和中部以前俯冲和挖出的海洋和大陆单元在古俯冲中的位置，（2）可以确定阿尔卑斯山下当前的地震速度异常。重新解释。我们的数据对于 SPP 4D-MB 中提出的大量项目也很有帮助和必要，特别是地震学、建模和构造变质研究。它符合RT1（岩石圈重组）、RT3（地壳+地幔变形）和AF-E（GEOLOG. Act.）框架。